1. Field of the Invention
The invention relates to a bearing apparatus for wheels.
2. Description of the Related Art
In vehicles such as automobiles, a bearing apparatus for wheels (hub unit) is used to support wheels so as to make the wheels rotatable. The bearing apparatus for wheels includes an outer ring, a hub shaft, and rolling elements. The outer ring is fixed to a suspension on a vehicle body side. The wheels are attached to the hub shaft. The rolling elements are provided between the outer ring and the hub shaft. In such a bearing apparatus for wheels, in order to restrain foreign matter such as water from entering, from a vehicle outer side, a bearing interior where the rolling elements are provided, a seal is attached to the vehicle outer side of the outer ring. A slinger that is contacted by the seal is attached to the vehicle outer side of the hub shaft (Japanese Patent Application Publication No. 2012-56412 (JP 2012-56412 A)).
A seal on the vehicle outer side is as depicted in FIG. 3. A seal 99 is attached to a vehicle-outer-side end of an outer ring 90. The seal 99 has inner lips 98a, 98b, 98c and an outer lip 98d. The inner lips 98a, 98b, 98c contact a slinger 91 attached to a hub shaft 92. The outer lip 98d contacts an outer peripheral surface 90a of the outer ring 90. The outer lip 98d contacts the outer peripheral surface 90a of the outer ring 90 to prevent foreign matter such as water (muddy water) from entering a bearing interior through a gap between a core 97 of the seal 99 and the outer ring 90.
In the bearing apparatus for wheels depicted in FIG. 3, the axially-outer-side outer peripheral surface 90a of the outer ring 90 is contacted by the outer lip 98d and is thus machined. Thus, even when the outer ring 90 is coated or plated, a base material is exposed, by machining, from a portion of the outer ring 90 that can be contacted by the outer lip 98d. Thus, in a machined surface K0 from which the base material is exposed, an area K1 located on a vehicle inner side with respect to a contact portion X contacted by the outer lip 98d is exposed to the exterior and may be rusted. When the externally exposed area K1 of the machined surface K0 is rusted and the rust progresses, sealing performance of the outer lip 98d is deteriorated.